Without regard to which rides better- SOA is typically going to be a custom job, and it may be difficult to find a shop willing to do the work if you don't plan on doing it yourself. Welding and parts fabrication are usually required. I also understand there are some states in which the SOA is illegal. The RE 4.5" Extreme Duty is bolt on, and can be done in a driveway with hand tools and a floor jack. It can be installed in a weekend, including the SYE.

That being said, I love my SOA and wouldn't really consider going back to SUA under any cicumstances. I helped install an RE 4.5ED on a buddies Jeep and have since wheeled with him. I'm pretty impressed with the flex of the RE, and my buddy is very happy with the ride quality on the highway.